Linear coated core/clad light source/collector

Abstract

An improved linear light source or light collector for a film scanner comprising an elongated, solid, light integrating, light conducting rod having an axial port at one end thereof through which a light beam is introduced into or directed out of the rod and an output/input strip extending generally parallel to its longitudinal axis. The rod preferably comprises a core of transparent glass having a first index of refraction with a cladding layer covering the core, except in a first elongated strip, of a glass having a second index of refraction. A coating of diffusely reflective paint is applied over the cladding and the first elongated strip, except in a second elongated strip (which defines the output/input strip), wherein the first and second elongated strips do not overlap one another. When used as a linear light source, light directed axially into the port propagates axially down the core by internal reflection off the cladding/core interface, but is diffusely scattered at the coating/core interface of the first elongated strip and again scattered at the coating/cladding interface until the scattered light escapes through the output strip to provide a line of diffusely scattered light. The illumination profile (variation of illumination along the length of the output strip) can be custom tailored, rather than simply being uniform, by controlling the area and location of the portion(s) of the cladding that is disrupted to form the first elongated strip. For example, it can be designed to provide more light at the ends of the strip than at the center. When used as a linear light collector, light is directed at the elongated strip and, through internal reflection, is reflected in the reverse direction to the axial end port and a photodetector to detect the instantaneous intensity of the light beam entering the input strip.

What is claimed is: 
     
       1. A solid, linear, light integrator of the type comprising elongated light integrating means having a port at one end thereof and a light exiting or entrance strip extending along the length thereof for emitting light entering the end port in a line, or admitting light for reflection through the port, the light integrating means further comprising: a core of transparent light conductive material having a first index of refraction;   a cladding layer covering the core, except in a first elongated strip extending longitudinally and parallel with the axis of the core, of a material having a second index of refraction; and   a coating of diffusely reflective material over the cladding and the first elongated strip and on the end port, except in a second elongated strip extending longitudinally and parallel with the axis of the core, wherein the first and second elongated strips do not overlap one another and are radially displaced from one another and with respect to the axis of the core sufficiently that light entering the second elongated strip and passing through the axis of the core does not directly impinge on the first elongated strip, or light reflected by the coating of diffusely reflective material over the first elongated strip and passing through the axis of the core does not directly exit through the second elongated strip,   whereby light propagates axially down the core by internal reflection off the cladding/core interface, but is diffusely scattered at the coating/core interface of the first elongated strip and at the coating/cladding interface so that light admitted at the end port is scattered and the scattered light escapes through the second elongated strip to provide a line of diffusely scattered light or light admitted through the second elongated strip is collected and directed through the end port.   
     
     
       2. The linear light integrator of claim 1 configured as a light source wherein: said second elongated strip provides a linear exit port for light entering the end port and scattered within the light integrating means; and   said first elongated strip is displaced radially from the second elongated strip in order to control the amount of light scattered directly from the first elongated strip to the linear exit port.   
     
     
       3. The linear light source of claim 2 wherein the radial displacement is less than 90°. 
     
     
       4. The linear light integrator of claim 2 wherein the first elongated strip has a relatively narrow width with respect to its length and wherein the width is varied along the length to lengthwise control the intensity of scattered light exiting the linear exit port. 
     
     
       5. The linear light integrator of claim 4 wherein the first elongated strip is wider nearer at least one end of the core than midway along its length. 
     
     
       6. The linear light integrator of claim 2 wherein the angle of displacement of the first and second elongated strips is decreased in order to increase the diffuseness of the light exiting the linear exit port. 
     
     
       7. The linear light integrator of claim 2 further comprising a third elongated strip extending lengthwise in the cladding and exposing the core and wherein: the third elongated strip is covered by the reflective coating; and   the second elongated strip in the coating is situated between the first and third elongated strips for providing highly diffusive light exiting the exit port.   
     
     
       8. The linear light integrator of claim 2 wherein the elongated light integrating means is generally cylindrical in cross-section and has a reflective mirror positioned at the other end thereof for reflecting light propagated axially down the core back toward the end port. 
     
     
       9. The linear light integrator of claim 1 wherein the elongated light integrating means is generally cylindrical in cross-section and has a reflective mirror positioned at the other end thereof for reflecting light propagated axially down the core back toward the end port. 
     
     
       10. The linear light integrator of claim 1 wherein the first elongated strip has a relatively narrow width with respect to its length and wherein the width is varied along the length to lengthwise control the intensity of scattered light along and within the core. 
     
     
       11. The linear light integrator of claim 10 wherein the first elongated strip is wider nearer at least one end of the core than midway along its length. 
     
     
       12. The linear light integrator of claim 1 wherein the first elongated strip comprises an elongated pattern of non-continuous openings in the cladding layer where cladding does not cover the core, the pattern modulated to lengthwise control the intensity of scattered light exiting the linear exit port. 
     
     
       13. The linear light integrator of claim 1 wherein the elongated light integrating means is generally cylindrical in cross-section and has a diffuse light reflector positioned near, but not in contact with, the other end thereof for reflecting light propagated axially down the core back toward the end port. 
     
     
       14. The linear light integrator of claim 1 configured as a light collector wherein: said second elongated strip provides a linear entry port for light directed therein; and   said first elongated strip is displaced radially from the second elongated strip in order to control the amount of light scattering of light entering the linear entry port depending on the point of entry along the entry port.   
     
     
       15. The linear light source of claim 14 wherein the radial displacement is less than 90°. 
     
     
       16. The linear light integrator of claim 14 wherein the first elongated strip has a relatively narrow width with respect to its length and wherein the width is varied along the length to lengthwise control the response to the intensity of light entering the linear entry port. 
     
     
       17. The linear light integrator of claim 16 wherein the first elongated strip is wider nearer at least one end of the core than midway along its length. 
     
     
       18. The linear light integrator of claim 14 wherein the angle of displacement of the first and second elongated strips is decreased in order to make the angular response of the end port more Lambertian. 
     
     
       19. The linear light integrator of claim 14 further comprising a third elongated strip extending lengthwise in the cladding and exposing the core and wherein: the third elongated strip is covered by the reflective coating; and   the second elongated strip in the coating is situated between the first and third elongated strips.   
     
     
       20. The linear light integrator of claim 14 wherein the first elongated strip comprises an elongated pattern of non-continuous openings in the cladding layer where cladding does not cover the core, the pattern modulated to lengthwise control the response to the intensity of light entering the linear entry port. 
     
     
       21. The linear light integrator of claim 14 wherein the elongated light integrating means is generally cylindrical in cross-section and has a diffuse light reflector positioned near, but not in contact with, the other end thereof for reflecting light propagated axially down the core back toward the end port. 
     
     
       22. The linear light integrator of claim 14 wherein the elongated light integrating means is generally cylindrical in cross-section and has a reflective mirror positioned at the other end thereof for reflecting light propagated axially down the core back toward the end port. 
     
     
       23. A solid, linear, light integrator of the type comprising elongated light integrating means having a port at one end thereof and a light exiting or entrance strip extending along the length thereof for emitting light entering the end port in a line, or admitting light for reflection through the port, the light integrating means further comprising: a core of transparent light conductive material having a first index of refraction and a generally polished surface except in a longitudinally extending pattern where the surface is treated to diffusely reflect light;   a cladding layer covering the surface of the core of a material having a second index of refraction; and   a coating of diffusely reflective material applied over the cladding layer and over the longitudinally extending pattern, except in an elongated strip extending longitudinally and parallel with the axis of the core and on the end port, wherein the longitudinally extending pattern and the elongated strip do not overlap one another and are radially displaced from one another and with respect to the axis of the core sufficiently that light entering the elongated strip, functioning as the light entrance strip, and passing through the axis of the core, does not directly impinge on the longitudinally extending pattern, or light reflected by the coating of diffusely reflective material over the longitudinally extending pattern does not pass through the axis of the core and directly exit through the elongated strip, operating as the exiting strip,   whereby light propagates axially down the core by internal reflection off the cladding/core interface, but is diffusely scattered at the longitudinally extending pattern and thereafter at the coating/cladding interface, so that light admitted at the end port is scattered and the scattered light escapes through the elongated light exiting strip to provide a line of diffusely scattered light or light admitted through the elongated entrance strip is collected and directed through the end port.   
     
     
       24. The linear light integrator of claim 23 wherein the surface treatment of the core in the longitudinally extending pattern comprises abrasion, etching or coating with particles. 
     
     
       25. A solid, linear, light integrator of the type comprising elongated light integrating means having a port at one end thereof and a light exiting or entrance strip extending along the length thereof for emitting light entering the end port in a line, or admitting light for reflection through the port, the light integrating means further comprising: an elongated core of transparent light conductive material having a first index of refraction and a generally polished surface and having a light scattering configuration formed therein in a longitudinally extending pattern;   a cladding layer covering the surface of the core of a material having a second index of refraction; and   a coating of diffusely reflective material applied over the cladding layer and over the longitudinally extending pattern of the light scattering configuration formed in the core, except in an elongated light exiting or entrance strip extending longitudinally and parallel with the axis of the core,   wherein the longitudinally extending pattern of the light scattering configuration is varied along the length of the core to tailor the light scattering characteristics within the core and the resultant brightness of light emitted through the light exiting strip along its longitudinal dimension or collected through the light entrance strip along its longitudinal dimension,   whereby light propagates axially down the core by internal reflection off the cladding/core interface, but is diffusely scattered at the longitudinally extending pattern and thereafter at the coating/cladding interface, so that light admitted at the end port is scattered and the scattered light escapes through the elongated strip to provide a line of diffusely scattered light or light admitted through the elongated strip is collected and escapes through the end port.   
     
     
       26. The linear light integrator of claim 25 wherein the configuration of the core to selectively scatter light comprises means incorporated into the light conductive material of the core for scattering light at an angle exceeding the angle of total internal reflection. 
     
     
       27. The linear light integrator of claim 26 wherein the light scattering means comprise voids or scattering particles selectively distributed lengthwise in the light conductive material. 
     
     
       28. The linear light integrator of claim 25 wherein the configuration of the clad core to selectively scatter light is effected by changing the index of refraction of the core or cladding layer along the length of the clad core. 
     
     
       29. The linear light integrator of claim 25 wherein the configuration of the clad core to selectively scatter light comprises a tapered clad core with a diameter which is reduced from a point near the entry port to a point at or near the other end of the clad core. 
     
     
       30. The linear light integrator of claim 1 further comprising a third elongated strip extending lengthwise in the cladding and exposing the core and wherein: the third elongated strip is covered by the reflective coating; and   the second elongated strip in the coating is situated between the first and third elongated strips.   
     
     
       31. A solid, linear, light integrator of the type comprising elongated light integrating means having a port at one end thereof and a light exiting or entrance strip extending along the length thereof for emitting light entering the end port in a line, or admitting light for reflection through the port, the light integrating means further comprising: an elongated core of transparent light conductive material having a first index of refraction and a generally polished surface;   a cladding layer covering the surface of the core of a material having a second index of refraction except in a longitudinally extending pattern varying in shape along the length of the core and forming a first elongated strip; and   a coating of diffusely reflective material applied over the cladding layer and over the longitudinally extending pattern of the first elongated strip, except in a second elongated light exiting or entrance strip extending longitudinally and parallel with the axis of the core,   wherein the longitudinally extending pattern of the first elongated strip covered by the diffusively reflective material functions as a light scattering configuration that is varied along the length of the core to tailor the light scattering characteristics within the core and the resultant brightness of light emitted through the light exiting strip along its longitudinal dimension or collected through the light entrance strip along its longitudinal dimension,   whereby light propagates axially down the core by internal reflection off the cladding/core interface, but is diffusely scattered at the longitudinally extending pattern and thereafter at the coating/cladding interface, so that light admitted at the end port is scattered and the scattered light escapes through the elongated strip to provide a line of diffusely scattered light or light admitted through the elongated strip is collected and escapes through the end port.   
     
     
       32. The linear light integrator of claim 31 wherein the first elongated strip comprises a pattern of non-continuous openings in the cladding layer exposing the core and covered by the diffusively reflective coating, the pattern modulated to lengthwise control the brightness of light emitted from the light exiting strip or to lengthwise control the response to the brightness of light entering the light entrance strip and directed to the end port. 
     
     
       33. The linear light integrator of claim 31 wherein the first elongated strip comprises a continuous opening in the cladding layer exposing the core and covered by the diffusively reflective coating, the opening varying in width to lengthwise control the brightness of light emitted from the light exiting strip or to lengthwise control the response to the brightness of light entering the light entrance strip and directed to the end port. 
     
     
       34. A solid, linear, light integrator of the type comprising elongated light integrating means having a port at one end thereof and a light exiting or entrance strip extending along the length thereof for emitting light entering the end port in a line, or admitting light for reflection through the port, the light integrating means further comprising: an elongated core of transparent light conductive material having a first index of refraction and a generally polished surface except in a longitudinally extending pattern varying in shape along the length of the core and forming a first elongated strip, wherein the generally polished surface is treated to diffusively reflect light;   a cladding layer covering the surface of the core including the first elongated strip of a material having a second index of refraction; and   a coating of diffusely reflective material applied over the cladding layer and over the longitudinally extending pattern of the first elongated strip, except in a second elongated light exiting or entrance strip extending longitudinally and parallel with the axis of the core,   wherein the longitudinally extending pattern of the first elongated strip covered by the diffusively reflective material functions as a light scattering configuration that is varied along the length of the core to tailor the light scattering characteristics within the core and the resultant brightness of light emitted through the light exiting strip along its longitudinal dimension or collected through the light entrance strip along its longitudinal dimension,   whereby light propagates axially down the core by internal reflection off the cladding/core interface, but is diffusely scattered at the longitudinally extending pattern and thereafter at the coating/cladding interface, so that light admitted at the end port is scattered and the scattered light escapes through the elongated strip to provide a line of diffusely scattered light or light admitted through the elongated strip is collected and escapes through the end port.   
     
     
       35. The linear light integrator of claim 34 wherein the first elongated strip comprises a pattern of non-continuous surface treatments of the core surface, the pattern modulated to lengthwise control the brightness of light emitted from the light exiting strip or to lengthwise control the response to the brightness of light entering the light entrance strip and directed to the end port. 
     
     
       36. The linear light integrator of claim 34 wherein the first elongated strip comprises a continuous surface treatment of the core surface varying in width to lengthwise control the brightness of light emitted from the light exiting strip or to lengthwise control the response to the brightness of light entering the light entrance strip and directed to the end port. 
     
     
       37. The linear light integrator of claim 34 wherein the surface treatment of the core comprises abrasion, etching or coating with particles.